Preparation method of carbon-coated current collector

Abstract

The invention relates to the technical field of current collectors, in particular to a preparation method of a carbon-coated current collector. The carbon coating slurry is prepared by using silver and copper fluoride loaded carbon nanotubes, polyether-ether-ketone, acrylic resin, polyvinylpyrrolidone and water as raw materials. According to the invention, nano-silver and copper fluoride are loaded on the carbon nanotube material, so that the conductivity of the current collector is enhanced; in addition, the specific surface area of the carbon nanotubes can be increased by loading copper fluoride and nano-silver, the interface interaction between the carbon nanotubes loaded with silver and copper fluoride and the aluminum foil is increased, and the bonding performance of the current collector can be further improved by improving the surface energy of the carbon nanotubes. And finally, the prepared current collector is subjected to heat treatment for 4-8 hours under the conditions of nitrogen atmosphere and 500-600 DEG C, so that the carbon-coated current collector is obtained, the resistance is reduced, and the conductivity and stripping resistance of the current collector are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of current collectors, and specifically to a preparation method of a carbon-coated current collector. Background Art

[0002] With the development of battery technology, the requirements for the performance and stability of battery current collectors are continuously increasing. Traditional battery current collectors use metal foils as conductive materials. However, traditional metal foils have some disadvantages. The conductivity of metal foils is limited, and they are prone to corrosion. To overcome these problems, in recent years, a method of preparing a current collector by applying a conductive carbon material layer on a metal foil has emerged to replace traditional metal foils and improve battery performance. This method involves applying a conductive carbon material layer on the surface of the metal foil to improve the conductivity, mechanical strength, and chemical stability of the current collector. The conductive carbon materials used can include carbon black, carbon nanotubes, graphene, etc. An adhesive is used to bond the conductive carbon material and the metal foil. The addition of these conductive carbon materials can ensure that the current collector has good conductivity and forms a uniform coating on the metal foil. However, the adhesives currently used are mainly organic compounds, which have problems such as non-conductivity, increased contact resistance, and low adhesive strength. Moreover, during the process of preparing the carbon-coated slurry, the carbon material is insoluble in water, which increases the difficulty of pulp preparation, and adding a dispersant will affect the performance of the formed battery.

[0003] To solve the above problems and improve conductivity and bonding strength, the present invention provides a preparation method of a carbon-coated current collector. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a carbon-coated current collector to solve the problems raised in the above background art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A preparation method of a carbon-coated current collector includes the following steps:

[0007] Step 1: Take carbon nanotubes loaded with silver and copper fluoride, polyether ether ketone, a resin adhesive, sodium dodecylbenzenesulfonate, and deionized water, and stir for 1 - 2 h to obtain a carbon-coated slurry;

[0008] Step 2: Take an aluminum foil, clean and dry it to obtain a pretreated aluminum foil; use the carbon-coated slurry to perform double-sided coating on the pretreated aluminum foil, and dry it to obtain a current collector; take the current collector and perform heat treatment in a nitrogen atmosphere for 4 h - 8 h to obtain a carbon-coated current collector.

[0009] Preferably, in step one, the method for preparing the carbon nanotubes loaded with silver and copper fluoride is as follows: Take the modified carbon nanotubes and add them to an aqueous silver nitrate solution. Ultrasonicate for 30 - 40 min, let stand for 5 - 7 h, add copper fluoride, heat to 140 - 150 °C, react for 10 - 12 h, dry, and calcine at 295 - 300 °C for 30 - 40 min to obtain the carbon nanotubes loaded with silver and copper fluoride.

[0010] Preferably, the method for preparing the modified carbon nanotubes is as follows: It includes the following steps:

[0011] S1: Take L-leucine and an aqueous sodium hydroxide solution, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 9, add N-dodecanoyl chloride dropwise, stir for 3 - 4 h, add dilute hydrochloric acid dropwise to adjust the pH value to 6, wash and extract to obtain compound A; Take sodium hydroxide and ethanol, stir evenly, add compound A, stir for 30 - 40 min, filter and dry to obtain compound B;

[0012] S2: Take compound B and an aqueous sodium hydroxide solution, stir evenly, cool down to 10 - 12 °C, add the treated carbon nanotubes and disperse for 10 - 12 h, filter and dry to obtain the modified carbon nanotubes.

[0013] Preferably, the method for preparing the treated carbon nanotubes is as follows: Take carbon nanotubes, sulfuric acid, and nitric acid, ultrasonically disperse for 120 - 130 min, filter, wash, and dry to obtain the treated carbon nanotubes.

[0014] Preferably, the method for preparing the carbon nanotubes is as follows: Mix graphite powder, catalyst, and sulfur evenly and press them into a rod as the anode graphite; Use a pure graphite rod as the cathode and prepare carbon nanotubes by arc discharge method.

[0015] Preferably, the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1.

[0016] Preferably, the resin binder is acrylic resin.

[0017] Preferably, the heat treatment temperature is 500 - 600 °C.

[0018] Preferably, the mass ratio of the carbon nanotubes loaded with silver and copper fluoride, polyetheretherketone, and resin binder is 30:(5 - 7):(13 - 15).

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0020] (1) The present invention uses the carbon nanotubes loaded with silver and copper fluoride, polyetheretherketone, acrylic resin, polyvinylpyrrolidone, and water as raw materials to prepare a carbon-coated slurry.

[0021] The present invention first prepares an alkylated amino acid compound B using L-leucine and N-dodecanoyl chloride; then uses this compound B to modify carbon nanotubes prepared by the arc discharge method. The alkyl chains in compound B wind around the carbon nanotubes, and the hydrophilic groups in compound B render the carbon nanotubes hydrophilic, and the carbon nanotubes are dispersed by the repulsive force between salts, thereby achieving the effect of rapid and uniform dispersion of the carbon nanotubes.

[0022] (2) The present invention loads silver nanoparticles and copper fluoride on the carbon nanotube material, enhancing the electrical conductivity of the current collector; loading copper fluoride and silver nanoparticles can also increase the specific surface area of the carbon nanotubes, increasing the interfacial interaction between the carbon nanotubes loaded with silver and copper fluoride and the aluminum foil, and can further improve the adhesion performance of the current collector by increasing the surface energy of the carbon nanotubes.

[0023] After modification with compound B, the modified carbon nanotubes are loaded with alkyl groups on the carbon nanotubes. The alkyl groups have good compatibility with the alkyl chains in polyetheretherketone, further improving the electrical conductivity and adhesion of the current collector.

[0024] (3) Finally, the current collector prepared by the present invention is heat-treated at 500 - 600 °C for 4 - 8 h under a nitrogen atmosphere to obtain a carbon-coated current collector. Through carbonization treatment, the interfacial structure between the aluminum foil and the carbon-coated slurry is changed, such that there is a region where metal and carbon are chemically bonded at the interface between the aluminum foil and the carbon-coated slurry, thereby further improving the electrical conductivity and peel resistance of the current collector and reducing its interfacial resistance. Detailed implementation manners

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] There are no special restrictions on the purchase manufacturers of all raw materials involved in the present invention. Exemplarily, it includes: the purity of graphite powder is greater than 99.5%, and it can be purchased from Guohua Reagent; the purity of graphite in the anode pure graphite rod is greater than 99.5%; the particle size of iron powder is 0.5 - 10 microns, the particle size of nickel powder is 1 - 10 microns, the particle size of cobalt powder is 1 - 10 microns, sulfur: sulfur powder promoter, the particle size is 50 - 100 nm; copper fluoride, which can be purchased from Hubei Chengfeng Chemical Co., Ltd.; polyetheretherketone: it can be purchased from Hubei Jusheng Technology Co., Ltd., model: JS5926; sodium dodecylbenzenesulfonate: it can be purchased from Guangzhou Jiarun Technology Co., Ltd., model: S60; acrylic resin: it can be purchased from Shandong Changyao New Materials Co., Ltd., model: CY-UC3.

[0027] Example 1: A preparation method of a carbon-coated current collector, comprising the following steps:

[0028] Step 1: Preparation of carbon nanotubes:

[0029] Mix 88.0 wt% of graphite powder, 10.0 wt% of catalyst, and 2.0 wt% of sulfur evenly, and press them into a rod as the anode graphite; use a pure graphite rod with a diameter equal to that of the anode as the cathode, and prepare carbon nanotubes by arc discharge method; the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1;

[0030] Step 2: Pretreatment of carbon nanotubes:

[0031] Take 0.5 g of carbon nanotubes, 80 mL of sulfuric acid, and 20 mL of nitric acid, ultrasonically disperse for 125 min, filter, wash, and dry to obtain pretreated carbon nanotubes;

[0032] Step 3: Preparation of modified carbon nanotubes:

[0033] S1: Take 2.5 g of L-leucine and 30 mL of a sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, dropwise add dilute hydrochloric acid to adjust the pH value to 9, dropwise add 4.7 mL of N-dodecanoyl chloride, stir for 3.5 h, dropwise add dilute hydrochloric acid to adjust the pH value to 6, wash and extract to obtain compound A; take 0.2 g of sodium hydroxide and 10 mL of ethanol, stir evenly, add compound A, stir for 35 min, filter and dry to obtain compound B;

[0034] S2: Take 5 g of compound B and 100 mL of a sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, cool down to 11 °C, add 0.1 g of pretreated carbon nanotubes and disperse for 11 h, filter and dry to obtain modified carbon nanotubes;

[0035] Step 4: Preparation of carbon nanotubes loaded with silver and copper fluoride:

[0036] Take 0.5 g of modified carbon nanotubes and add them to 500 mL of a silver nitrate aqueous solution with a concentration of 0.03 mol / L, ultrasonically disperse for 35 min, let stand for 6 h, add 10 g of copper fluoride, heat up to 145 °C, react for 11 h, dry, and calcine at 295 °C for 35 min to obtain carbon nanotubes loaded with silver and copper fluoride;

[0037] Step 5: Preparation of carbon-coated slurry:

[0038] Take 30 kg of carbon nanotubes loaded with silver and copper fluoride, 5 kg of polyether ether ketone, 15 kg of acrylic resin, 0.5 kg of sodium dodecylbenzenesulfonate, and 50 kg of deionized water, and stir for 1.5 h to obtain a carbon-coated slurry;

[0039] Step Six: Preparation of Carbon-Coated Current Collector:

[0040] Take an aluminum foil with a thickness of 13 μm, clean and dry it to obtain a pretreated aluminum foil; use a carbon-coated slurry to coat both sides of the pretreated aluminum foil, with a coating thickness of 1 μm, and dry it to obtain a current collector; take the current collector, and heat-treat it in a nitrogen atmosphere at 550 °C for 6 h to obtain a carbon-coated current collector.

[0041] Example 2: A method for preparing a carbon-coated current collector, comprising the following steps:

[0042] Step One: Preparation of Carbon Nanotubes:

[0043] Mix 88.0 wt% graphite powder, 10.0 wt% catalyst, and 2.0 wt% sulfur evenly, and press them into a rod as the anode graphite; use a pure graphite rod with a diameter equal to that of the anode as the cathode, and prepare carbon nanotubes by arc discharge method; the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1.

[0044] Step Two: Pretreatment of Carbon Nanotubes:

[0045] Take 0.5 g of carbon nanotubes, 80 mL of sulfuric acid, and 20 mL of nitric acid, ultrasonically disperse them for 120 min, filter, wash, and dry to obtain pretreated carbon nanotubes.

[0046] Step Three: Preparation of Modified Carbon Nanotubes:

[0047] S1: Take 2.5 g of L-leucine and 30 mL of a sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, add dilute hydrochloric acid to adjust the pH value to 9, add 4.7 mL of N-dodecanoyl chloride, stir for 3 h, add dilute hydrochloric acid to adjust the pH value to 6, wash and extract to obtain Compound A; take 0.2 g of sodium hydroxide and 10 mL of ethanol, stir evenly, add Compound A, stir for 30 min, filter and dry to obtain Compound B.

[0048] S2: Take 5 g of Compound B and 100 mL of a sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, cool down to 10 °C, add 0.1 g of pretreated carbon nanotubes and disperse for 10 h, filter and dry to obtain modified carbon nanotubes.

[0049] Step Four: Preparation of Carbon Nanotubes Loaded with Silver and Copper Fluoride:

[0050] Take 0.5 g of modified carbon nanotubes and add them to 500 mL of a silver nitrate aqueous solution with a concentration of 0.03 mol / L, ultrasonically disperse for 30 min, let stand for 5 h, add 10 g of copper fluoride, heat up to 140 °C, react for 12 h, dry, and calcine at 295 °C for 40 min to obtain carbon nanotubes loaded with silver and copper fluoride.

[0051] Step Five: Preparation of carbon-coated slurry:

[0052] Take 30 kg of carbon nanotubes loaded with silver and copper fluoride, 5 kg of polyether ether ketone, 15 kg of acrylic resin, 0.5 kg of sodium dodecylbenzenesulfonate, and 50 kg of deionized water, stir for 1 - 2 h to obtain the carbon-coated slurry;

[0053] Step Six: Preparation of carbon-coated current collector:

[0054] Take an aluminum foil with a thickness of 13 μm, clean and dry it to obtain the pretreated aluminum foil; use the carbon-coated slurry to coat both sides of the pretreated aluminum foil, with the slurry coating thickness of 1 μm, and dry it to obtain the current collector; take the current collector, and heat-treat it in a nitrogen atmosphere at 500 °C for 8 h to obtain the carbon-coated current collector.

[0055] Example 3: A method for preparing a carbon-coated current collector, comprising the following steps:

[0056] Step One: Preparation of carbon nanotubes:

[0057] Mix 88.0 wt% of graphite powder, 10.0 wt% of catalyst, and 2.0 wt% of sulfur evenly, and press them into a rod as the anode graphite; use a pure graphite rod with a diameter equal to that of the anode as the cathode, and prepare carbon nanotubes by arc discharge method; the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1;

[0058] Step Two: Pretreatment of carbon nanotubes:

[0059] Take 0.5 g of carbon nanotubes, 80 mL of sulfuric acid, and 20 mL of nitric acid, ultrasonically disperse for 130 min, filter, wash, and dry to obtain the treated carbon nanotubes;

[0060] Step Three: Preparation of modified carbon nanotubes:

[0061] S1: Take 2.5 g of L-leucine, 30 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, dropwise add dilute hydrochloric acid to adjust the pH value to 9, dropwise add 4.7 mL of N-dodecanoyl chloride, stir for 4 h, dropwise add dilute hydrochloric acid to adjust the pH value to 6, wash and extract to obtain Compound A; take 0.2 g of sodium hydroxide, 10 mL of ethanol, stir evenly, add Compound A, stir for 40 min, filter and dry to obtain Compound B;

[0062] S2: Take 5 g of Compound B, 100 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, cool down to 12 °C, add 0.1 g of the treated carbon nanotubes and disperse for 12 h, filter and dry to obtain the modified carbon nanotubes;

[0063] Step 4: Preparation of silver- and copper fluoride-loaded carbon nanotubes:

[0064] Take 0.5 g of modified carbon nanotubes and add them to 500 mL of an aqueous silver nitrate solution with a concentration of 0.03 mol / L. Sonicate for 40 min, let stand for 5 - 7 h, add 10 g of copper fluoride, heat to 150 °C, react for 12 h, dry, and calcine at 300 °C for 40 min to obtain silver- and copper fluoride-loaded carbon nanotubes;

[0065] Step 5: Preparation of carbon-coated slurry:

[0066] Take 30 kg of silver- and copper fluoride-loaded carbon nanotubes, 5 kg of polyether ether ketone, 15 kg of acrylic resin, 0.5 kg of sodium dodecylbenzenesulfonate, and 50 kg of deionized water, stir for 1 - 2 h to obtain a carbon-coated slurry;

[0067] Step 6: Preparation of carbon-coated current collector:

[0068] Take an aluminum foil with a thickness of 13 μm, clean and dry it to obtain a pretreated aluminum foil; use the carbon-coated slurry to coat both sides of the pretreated aluminum foil, with a slurry coating thickness of 1 μm, dry to obtain a current collector; take the current collector and heat-treat it in a nitrogen atmosphere at 550 °C for 8 h to obtain a carbon-coated current collector.

[0069] Comparative Example 1: Without using Compound B to modify the carbon nanotubes, the rest is the same as in Example 1, including the following steps:

[0070] Step 1: Preparation of carbon nanotubes:

[0071] Mix 88.0 wt% of graphite powder, 10.0 wt% of catalyst, and 2.0 wt% of sulfur evenly and press them into a rod as the anode graphite; use a pure graphite rod with a diameter equal to that of the anode as the cathode, and prepare carbon nanotubes by arc discharge method; the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1;

[0072] Step 2: Pretreatment of carbon nanotubes:

[0073] Take 0.5 g of carbon nanotubes, 80 mL of sulfuric acid, and 20 mL of nitric acid, sonicate and disperse for 125 min, filter, wash, and dry to obtain pretreated carbon nanotubes;

[0074] Step 3: Preparation of modified carbon nanotubes:

[0075] Take 1 g of pretreated carbon nanotubes, 7 g of N,N'-dicyclohexylcarbodiimide, and 24 g of 1,6-hexanediamine, heat to 90 °C, stir for 38 h, filter, wash, and dry to obtain modified carbon nanotubes;

[0076] Step 4: Preparation of silver- and copper fluoride-loaded carbon nanotubes:

[0077] Take 0.5 g of modified carbon nanotubes and add them to 500 mL of an aqueous silver nitrate solution with a concentration of 0.03 mol / L. Ultrasonicate for 35 min, let stand for 6 h, add 10 g of copper fluoride, heat to 145 °C, react for 11 h, dry, and calcine at 295 °C for 35 min to obtain carbon nanotubes loaded with silver and copper fluoride;

[0078] Step Five: Preparation of the carbon-coated slurry:

[0079] Take 30 kg of carbon nanotubes loaded with silver and copper fluoride, 5 kg of polyetheretherketone, 15 kg of acrylic resin, 0.5 kg of sodium dodecylbenzenesulfonate, and 50 kg of deionized water, and stir for 1.5 h to obtain the carbon-coated slurry;

[0080] Step Six: Preparation of the carbon-coated current collector:

[0081] Take an aluminum foil with a thickness of 13 μm, clean and dry it to obtain the pretreated aluminum foil; use the carbon-coated slurry to perform double-sided coating on the pretreated aluminum foil, with the slurry coating thickness of 1 μm, dry to obtain the current collector; take the current collector and heat-treat it in a nitrogen atmosphere at 550 °C for 6 h to obtain the carbon-coated current collector.

[0082] Comparative Example 2: Do not load copper fluoride on the carbon nanotube material, and the rest is the same as in Example 1, including the following steps:

[0083] Step One: Preparation of carbon nanotubes:

[0084] Mix 88.0 wt% of graphite powder, 10.0 wt% of catalyst, and 2.0 wt% of sulfur evenly and press them into a rod as the anode graphite; use a pure graphite rod with a diameter equal to that of the anode as the cathode, and prepare carbon nanotubes by arc discharge method; the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1;

[0085] Step Two: Pretreatment of carbon nanotubes:

[0086] Take 0.5 g of carbon nanotubes, 80 mL of sulfuric acid, and 20 mL of nitric acid, ultrasonically disperse for 125 min, filter, wash, and dry to obtain the pretreated carbon nanotubes;

[0087] Step Three: Preparation of modified carbon nanotubes:

[0088] S1: Take 2.5 g of L-leucine and 30 mL of a sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 9, add 4.7 mL of N-dodecanoyl chloride dropwise, stir for 3.5 h, add dilute hydrochloric acid dropwise to adjust the pH value to 6, wash and extract to obtain compound A; take 0.2 g of sodium hydroxide and 10 mL of ethanol, stir evenly, add compound A, stir for 35 min, filter and dry to obtain compound B;

[0089] S2: Take 5 g of compound B and 100 mL of a sodium hydroxide aqueous solution with a concentration of 1 mol / L, stir evenly, cool down to 11 °C, add 0.1 g of treated carbon nanotubes and disperse for 11 h, filter and dry to obtain modified carbon nanotubes;

[0090] Step Four: Preparation of carbon nanotubes loaded with silver and copper fluoride:

[0091] Take 0.5 g of modified carbon nanotubes and add them to 500 mL of a silver nitrate aqueous solution with a concentration of 0.03 mol / L, ultrasonicate for 35 min, let stand for 6 h, raise the temperature to 145 °C, react for 11 h, dry, and calcine at 295 °C for 35 min to obtain carbon nanotubes loaded with silver and copper fluoride;

[0092] Step Five: Preparation of carbon-coated slurry:

[0093] Take 30 kg of carbon nanotubes loaded with silver and copper fluoride, 5 kg of polyetheretherketone, 15 kg of acrylic resin, 0.5 kg of sodium dodecylbenzenesulfonate, and 50 kg of deionized water, stir for 1.5 h to obtain carbon-coated slurry;

[0094] Step Six: Preparation of carbon-coated current collector:

[0095] Take an aluminum foil with a thickness of 13 μm, clean and dry it to obtain a pretreated aluminum foil; use the carbon-coated slurry to coat both sides of the pretreated aluminum foil, with the slurry coating thickness of 1 μm, dry to obtain a current collector; take the current collector, and heat-treat it in a nitrogen atmosphere at 550 °C for 6 h to obtain a carbon-coated current collector.

[0096] Comparative Example 3: Reduce the addition amount of polyetheretherketone, and the rest is the same as in Example 1, including the following steps:

[0097] Step One: Preparation of carbon nanotubes:

[0098] Mix 88.0 wt% of graphite powder, 10.0 wt% of catalyst, and 2.0 wt% of sulfur evenly and press them into a rod as the anode graphite; use a pure graphite rod with a diameter equal to that of the anode as the cathode, and prepare carbon nanotubes by arc discharge method; the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1;

[0099] Step Two: Pretreatment of carbon nanotubes:

[0100] Take 0.5 g of carbon nanotubes, 80 mL of sulfuric acid, and 20 mL of nitric acid, ultrasonically disperse for 125 min, filter, wash, and dry to obtain the treated carbon nanotubes;

[0101] Step Three: Preparation of modified carbon nanotubes:

[0102] S1: Take 2.5 g of L-leucine and 30 mL of a 1 mol / L aqueous sodium hydroxide solution, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 9, add 4.7 mL of N-dodecanoyl chloride dropwise, stir for 3.5 h, add dilute hydrochloric acid dropwise to adjust the pH value to 6, wash and extract to obtain Compound A; take 0.2 g of sodium hydroxide and 10 mL of ethanol, stir evenly, add Compound A, stir for 35 min, filter and dry to obtain Compound B;

[0103] S2: Take 5 g of Compound B and 100 mL of a 1 mol / L aqueous sodium hydroxide solution, stir evenly, cool down to 11 °C, add 0.1 g of the treated carbon nanotubes and disperse for 11 h, filter and dry to obtain the modified carbon nanotubes;

[0104] Step Four: Preparation of carbon nanotubes loaded with silver and copper fluoride:

[0105] Take 0.5 g of the modified carbon nanotubes and add them to 500 mL of a 0.03 mol / L aqueous silver nitrate solution, ultrasonically for 35 min, let stand for 6 h, add 10 g of copper fluoride, heat up to 145 °C, react for 11 h, dry, and calcine at 295 °C for 35 min to obtain the carbon nanotubes loaded with silver and copper fluoride;

[0106] Step Five: Preparation of carbon-coated slurry:

[0107] Take 30 kg of the carbon nanotubes loaded with silver and copper fluoride, 1 kg of polyetheretherketone, 15 kg of acrylic resin, 0.5 kg of sodium dodecylbenzenesulfonate, and 50 kg of deionized water, stir for 1.5 h to obtain the carbon-coated slurry;

[0108] Step Six: Preparation of carbon-coated current collector:

[0109] Take an aluminum foil with a thickness of 13 μm, clean and dry it to obtain the pretreated aluminum foil; use the carbon-coated slurry to perform double-sided coating on the pretreated aluminum foil, with a slurry coating thickness of 1 μm, dry to obtain the current collector; take the current collector and perform heat treatment in a nitrogen atmosphere at 550 °C for 6 h to obtain the carbon-coated current collector.

[0110] Comparative Example 4: When preparing the carbon-coated current collector, the heat treatment condition is heat treatment at 550 °C for 5 h, and the rest is the same as in Example 1, including the following steps:

[0111] Step One: Preparation of carbon nanotubes:

[0112] Mix 88.0 wt% graphite powder, 10.0 wt% catalyst, and 2.0 wt% sulfur evenly and press them into a rod as the anode graphite; use a pure graphite rod with a diameter equal to that of the anode as the cathode, and prepare carbon nanotubes by arc discharge method; the catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:1.

[0113] Step Two: Pretreatment of carbon nanotubes:

[0114] Take 0.5 g of carbon nanotubes, 80 mL of sulfuric acid, and 20 mL of nitric acid, ultrasonically disperse for 125 min, filter, wash, and dry to obtain the treated carbon nanotubes.

[0115] Step Three: Preparation of modified carbon nanotubes:

[0116] S1: Take 2.5 g of L-leucine and 30 mL of a 1 mol / L sodium hydroxide aqueous solution, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 9, add 4.7 mL of N-dodecanoyl chloride dropwise, stir for 3.5 h, add dilute hydrochloric acid dropwise to adjust the pH value to 6, wash and extract to obtain Compound A; take 0.2 g of sodium hydroxide and 10 mL of ethanol, stir evenly, add Compound A, stir for 35 min, filter and dry to obtain Compound B.

[0117] S2: Take 5 g of Compound B and 100 mL of a 1 mol / L sodium hydroxide aqueous solution, stir evenly, cool down to 11 °C, add 0.1 g of the treated carbon nanotubes and disperse for 11 h, filter and dry to obtain the modified carbon nanotubes.

[0118] Step Four: Preparation of carbon nanotubes loaded with silver and copper fluoride:

[0119] Take 0.5 g of the modified carbon nanotubes and add them to 500 mL of a 0.03 mol / L silver nitrate aqueous solution, ultrasonically for 35 min, let stand for 6 h, add 10 g of copper fluoride, heat up to 145 °C, react for 11 h, dry, and calcine at 295 °C for 35 min to obtain the carbon nanotubes loaded with silver and copper fluoride.

[0120] Step Five: Preparation of carbon-coated slurry:

[0121] Take 30 kg of the carbon nanotubes loaded with silver and copper fluoride, 5 kg of polyetheretherketone, 15 kg of acrylic resin, 0.5 kg of sodium dodecylbenzenesulfonate, and 50 kg of deionized water, stir for 1.5 h to obtain the carbon-coated slurry.

[0122] Step Six: Preparation of carbon-coated current collector:

[0123] Take an aluminum foil with a thickness of 13 μm, clean and dry it to obtain a pretreated aluminum foil; use a carbon coating slurry to coat both sides of the pretreated aluminum foil, with the slurry coating thickness being 1 μm, and dry it to obtain a current collector; take the current collector and heat-treat it in a nitrogen atmosphere at 550 °C for 5 h to obtain a carbon-coated current collector.

[0124] Experiment:

[0125] Perform performance tests on the carbon-coated current collectors prepared in Examples 1 to 3 and Comparative Examples 1 to 3. Use a probe tester to test the sheet resistance of the carbon-coated current collector to characterize the conductive performance of the carbon-coated current collector. Use a universal tensile machine to perform a tensile peel test on the carbon-coated current collector after bonding and compressing it with tape.

[0126]

[0127] Conclusion: It can be seen from the comparison of the data in the table that in Comparative Example 1, compound B is not used to modify the carbon nanotubes, and the dispersion of the carbon nanotubes is not good, which affects the conductive performance and bonding performance of the carbon-coated current collector. In Comparative Example 2, copper fluoride is not loaded on the carbon nanotube material, resulting in a decrease in conductive performance, a decrease in the amount of substances loaded on the carbon nanotubes, a decrease in specific surface area, and a reduction in the interfacial interaction between the carbon nanotubes and the aluminum foil, resulting in poor bonding performance. In Comparative Example 3, the addition amount of polyether ether ketone is reduced, and the addition amount of polyether ether ketone is 1 kg, resulting in a decrease in the compatibility of the carbon nanotubes loaded with silver and copper fluoride in the coating, and a decrease in the conductive performance and bonding performance of the carbon-coated current collector. When preparing the carbon-coated current collector in Comparative Example 4, the heat treatment condition is heat treatment at 550 °C for 5 h. At this time, the heat treatment time is reduced, and the performance of the carbon-coated current collector decreases.

[0128] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a carbon-coated current collector, characterized in that: It includes the following steps: Step 1: Take carbon nanotubes loaded with silver and copper fluoride, polyether ether ketone, resin binder, sodium dodecylbenzenesulfonate, and deionized water, and stir for 1 - 2 h to obtain carbon-coated slurry; Step 2: Take aluminum foil, clean and dry it to obtain pretreated aluminum foil; use the carbon-coated slurry to coat both sides of the pretreated aluminum foil, and dry it to obtain a current collector; Take the current collector and heat-treat it in a nitrogen atmosphere for 4 h - 8 h to obtain a carbon-coated current collector.

2. The method for preparing a carbon-coated current collector according to claim 1, characterized in that: In Step 1, the preparation method of the carbon nanotubes loaded with silver and copper fluoride is as follows: Take modified carbon nanotubes and add them to an aqueous silver nitrate solution, ultrasonically vibrate for 30 - 40 min, let it stand for 5 - 7 h, add copper fluoride, raise the temperature to 140 - 150 °C, react for 10 - 12 h, dry, and calcine at 295 - 300 °C for 30 - 40 min to obtain carbon nanotubes loaded with silver and copper fluoride.

3. The method for preparing a carbon-coated current collector according to claim 2, characterized in that: The preparation method of the said modified carbon nanotubes is as follows: It includes the following steps: S1: Take L-leucine and an aqueous sodium hydroxide solution, stir evenly, add dilute hydrochloric acid dropwise to adjust the pH value to 9, add N-dodecanoyl chloride dropwise, stir for 3 - 4 h, add dilute hydrochloric acid dropwise to adjust the pH value to 6, wash and extract to obtain compound A; Take sodium hydroxide and ethanol, stir evenly, add compound A, stir for 30 - 40 min, filter and dry to obtain compound B; S2: Take compound B and an aqueous sodium hydroxide solution, stir evenly, cool down to 10 - 12 °C, add the treated carbon nanotubes and disperse for 10 - 12 h, filter and dry to obtain modified carbon nanotubes.

4. The method for preparing a carbon-coated current collector according to claim 3, characterized in that: The preparation method of the said treated carbon nanotubes is as follows: Take carbon nanotubes, sulfuric acid, and nitric acid, ultrasonically disperse for 120 - 130 min, filter, wash, and dry to obtain treated carbon nanotubes.

5. The method for preparing a carbon-coated current collector according to claim 4, characterized in that: The preparation method of the said carbon nanotubes is as follows: Mix graphite powder, catalyst, and sulfur evenly and press them into a rod as the anode graphite; Use a pure graphite rod as the cathode and prepare carbon nanotubes by arc discharge method.

6. The method for preparing a carbon-coated current collector according to claim 5, characterized in that: The said catalyst is iron powder, nickel powder, and cobalt powder with a molar ratio of 1:1:

1.

7. The method for preparing a carbon-coated current collector according to claim 1, characterized in that: The said resin binder is acrylic resin.

8. The method for preparing a carbon-coated current collector according to claim 1, characterized in that: The heat treatment temperature is 500 - 600 °C.

9. The method for preparing a carbon-coated current collector according to claim 1, characterized in that: The mass ratio of the carbon nanotubes loaded with silver and copper fluoride, polyether ether ketone, and resin binder is 30:(5 - 7):(13 - 15).

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